Selective apparatus for systems of communication.



f corresponding or coperating contacts of the relays are connected to the individual lines or circuits to be selected, thus, in the relay Rappear the terminals of lines #1 to #10; in relay R2 appear the terminals of lines #11 to #20; and inrelay R4 appear the terminals of lines #21 to #30. Each of the 'pairs a, b, c, etc., is connected to the vsingle the cable C. As these pairs' are distributed 1 air of contacts in one" of the units relays RS R, etch Thus, the' pair a appears Y only in the relay R', the pair f appears only in therelay R11., and so forth. I have shown the contacts of all the units're'lays connected on one side to a common circuit 12, to which isconnected a-v telephone O. I have shown line #1,.which is the first outside line o n relay R, connected to a telephone S5 and 1t is to be understood that all the other terminals may be connected to similar or any desired apparatus.

The operation of selecting any one of the lines represented o n the tens relays is as follows: Suppose it be desired to connect the telephone O with the telephone S;the line circuit leading to Sis #1, which appears only in vthe terminals on relay R. Hence the operator ress'es the key T to energize the rela R t rough the following circuit; B, 8, l 2,]R and round. Relay R in pulling up connects al of the lines #1 to #10 onto the pairs of wires (1,5, c, d, etc., in

among the relays R, R2,R5, etc., it follows 'that we havethus connected the lines #l to #l0 to the unitsrelays respectively from R to R19, and by energizing any desired one of these relayswe may select any one Aofthe individual lines which have become thus connected. In the present case the operator depresses the keyU, which closes the circuit-` of the relay R as follows: B, 10, U', 1, R and ground. Relay R in pulling up connects the pair' of wires a to the pair 12 -leading to the telephone O, .and thus as long as the two keys T and U are vdepressed this connection will remain established.

To take another example, suppose it be desired to select and connect wlth line #17: the keys T2, and U7 are depressed. Similarly by varying the combination of tens and umts keys and thereby energizing the tens and units relays in corresponding comvbinations, selected.

I have employed the keys herein shown any deslred line or lines may be for, purposes Vof illustration because theyv constltute the simplest and best known form of circuit closers, but in practice other forms of circuit closers arey more frequently employed. Thus in adapting this arrangement to a signaling or telephone system, instead of depressingtwo keys in order to select a- ,desired circuit, it is simpler to simultaneously close two contacts constituting terminuls of the desired relays. Such an arrangepurposes of illustration, the invention lying not in the circuit closers used yin the initial control of the circuit system, but in the arrangement of the tens and units relays, and

their circuits, used in various combinations so as to produce a total number of possible` selections andconnections greater than the numberof relays employed. It should be observed thatr the relation of these relays is not limited to a decimal relation.4 Thus, the number of contacts carried on the relays R, R2, etc., is limited only by the requirements of good practice, and the possibility of obtaining suiiicient power in the actuating electromagnet. Similarly, the number ofrelays R, R2 and R4L which may be employed is not limited, nor is the number of the units relays R', R2, etc. For example,

twenty relays R, R2, etc., could be provided each of which had its ten pairs of contacts multipled in a manner similar to those in the figure. Any one of two hundred lines could thus be selected. Or, ten relays R, R2, etc. may be provided each with twenty pairs of contacts. It would then be necessary to provide twenty pairs of wires in the cable (34 and twenty individual relays R, RafR, etc. Numerous other arrangements will suggest' themselves. v

In' applying this invention to a telephone exchange, the circuits 1 to 30 shown herein .would be subscribers lines, and the circuit 12 a trunk or other connective circuit.

I have described my controlling relays as single wound, and depending entirely upon the selective circuit closers. By providing each relay with a secondrwinding, and a pair of controlling contacts therefor on its armature, and by running a common battery wire. to all of these contacts as shown in Fig. 2 each relay may be made to close its own circuit when it is energized, so that it will remain energized as long as the common battery locking wire is intact. To unlock the relay I place a key inl this common battery wire so that it'may be opened at will for restoring purposes. A still simpler arrangement, which is also self-locking, is to connect one of the contacts o n'the relay armature with the battery wire, and Athe other with a point ,on the battery side of the single 'windin This arrangement is shown 1n Fig. 3.

hus a temporary closure 

